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(NoModeL) 2 Sheets-Sheet 2.

W. T. FORSTER.

. AIR COMPRESSOR! N0 384,356. Patented June 12, 1888.

WITNESSES, A HYVE/YTdR- Width/V34. l Y4 f I NITED rarns a'rnsrr imi'cnoWILLlAlVI T. FORSTER, OF ERIE, PENNSYLVANIA.

AIR-COMPRESSOR.

SPECIFICATION forming part of Letters Patent No. dated June 1888-Application filed June 3, 1887. Serial No. 240,123.

To all whom it may concern:

Be it known that 1, WILLIAM T. FORSTER, a citizen of the United States,and a resident of Erie, in the county of Erie and State of Pennsylvania,have invented certain new and useful Improvements in Air-Compressors, ofwhich the following is a specification.

My invention refers to compressors for compressing air or other gases,and is intended to produce a compressor in which a greater quantity orvolume of compressed air can be obtained by the application of a slightincrease of power; and it consists in an improved construction of thecompressor by which the exhaust-steam from the drivingengine is usedtoincrease the quantity of air to be compressed in the cylinder.

In the accompanying drawings, illustrating my improvement, in which likeletters indicate like parts, Figure 1 is a sectional elevavation of myimproved compressor. Fig. 2is a plane view of the compressor shown inFig. 1, through theline as m, looking down from the top.

My improvement consists, essentially, in combining with the air-cylinderin which the air is compressed a second or auxiliary cylindercommunicating with the air-cylinder and provided with a piston soconstructed and arranged as to be operated upon or moved by theapplication of the exhaust-steam as the latter comes from thesteam-cylinder,by means of which the air in the auxiliary cylinder isthrown into the air-cylinder and added to the air already in the latter,and thus the volume or quantity of air to be compressed in theaircylinder is increased and a greater quantity or volume of compressedair obtained at each stroke of the compressing piston.

The drawings show my improvement applied to a single-acting compressorwhere the air is compressed by the movement of the piston in onedirection only; but it may be used equally well on a double-actingcompressor in which the air is compressed by each stroke of the piston.

In the construction and arrangement of my improved compressor shown inthe drawings, A is a vertical single-acting air-cylinder in which theair is compressed by the piston 1?. At the top or upper end of thecylinder are (No model.)

the usual inlet and outlet or delivery valves, 2 and 1. At the bottom oropposite end of the cylinder, and below the piston I? when on its lowercenter or at the end of its stroke, is a 5 second or auxiliary cylinder,B, of the same capacity as the cylinder A, and opening directly into thelatter. This cylinder B is inclosed on the sides and open at the top,where it communicates with the cylinder A, and at thickness of thepistonhead P, and between these channels I are openings K, by which airenters the cylinder, and which are covered by the piston-head 1? whenthe latter is at the end of its stroke, and are thus closed, so that theair in the cylinder cannot escape through the 7 5 same.

In the piston P are a number of valves, 1), arranged so as to openupward and allow the air to pass into the cylinder through the piston. aseries of tubes, H, arranged outside of the cylinder A, having theirlower ends opening into the cylinder B and their upper ends into thecylinder A above the piston P.

On account of the several openings 1, H,

and p the air in the cylinder B, when forced by the piston O, can passfreely and quickly into the air-cylinder A.

Surrounding the air-cylinder A and supported on posts, as shown in Fig.l, is a cireu-po lar cylinder,E, containing a piston, F, arranged toslide back and forth in the cylinder. To this piston F are secured theupper ends of the rods D, which extend into the cylinder E, the

lower ends of which are connected with the piston O in the auxiliarycylinder B. As will be understood from the drawings, as the piston Fslides upward in the cylinder E it draws the rods D with it, and thusmoves the piston O in the auxiliary cylinder B toward the open ing inthe air-cylinder A.

The cylinder E is inclosed on all sides and In the walls of the 6Besides the channels I and valves 1; are 80 constructed so as to besteam-tight. At the bottom or lower end of this cylinder is the inlet m,and at or near the top is the outlet 6, by means of which the air in thecylinder escapes as the piston F advances toward the top. The inlet mcommunicates by the pipe M with the steam-cylinder of thedriving-engine, by which the exhaust-steam from the steam-cylinderpasses into the cylinder E under the piston F, and, filling the cylinderwith steam, forces the piston upward, and the latter as-it moves drawsup the rods D and moves the piston O in the cylinder B. The steamremains in the cylinder E until the engine opens the slide-valve n inthe pipe N, when the steam at once escapes through the opening m andpasses from the cylinder.

On top of the cylinder E are two buffer-cylinders or dash-pots, L,(shown also in Fig. 2,) provided with the pistons Z and rods Z. Thepistons Z are connected by means of the rods G with the piston F, andthus move with the latter. The rods Z serve to guide the pistons L intheir ascent and cause them to strike the buffers 0 evenly. Thecylinders L serve to check the force of the piston F, and as the buffer0 may be moved toward or away from the cylinder E by means of thescrew-rods L the length of stroke of the piston F can be regulated asdesired.

As'the steam fills the cylinder E with great rapidity, it moves thepiston F, and consequently the piston O, veryquickly, and thus throwsthe air in the cylinder B into the cylinder A while the piston is on itscenter, and on account of the several openingsinto the aircylinder, thechannels I, tubes H, and valves P the air can pass immediately into thelatter cylinder. Moreover, as the pistons F and 0 move with so muchrapidity,itis not necessary to pack them so carefully or take so muchcare to make the various joints tight.

Several rods D connect the piston O with' the piston F, and thus theformer piston is made to slide evenly and smoothly in the cylinder B.

The action of the compressor thus constructed is as follows: As thepiston compresses the air in the air-cylinder A, air enters thecylinders A and B behind the piston through the openings K and fills thecylinder with atmospheric air. When on its return-stroke the piston Phas almost reached its lowest position, it covers these openings K, thusclosing them, and slides past the upper ends of the channels I and tubesH. Hence, when the piston P has reached its lowest position or is on itslower center, the two cylinders A and B, filled with ordinary oratmospheric air, communicate with each other through the tubes H andchannels I. While the piston P is in this position or is on its lowercenter, the exhaust valve or port of the driving-engine isopen,admitting the steam to the pipe M and inlet on into the cylinder Eunder the piston F, where it at once drives the piston up in thecylinder, and hence by means of the rods D slides the piston G in theThe piston G is held in the upper end of the cylinder B by the steam inthe cylinder E as the piston P starts on its upward stroke. The lattersliding past the openings of the channels I and tubes H closes the same,and thus confines the air in the air cylinder. As the piston commencesits upward movement, the slidevalve n is opened by the engine and thesteam in the cylinder E allowed to escape, when the pistons F and 0 fallby gravity and the cylinder B is again filled with air. As will thus beseen, while the compressing-piston P is on its lower center, and beforeit moves on its upward stroke, the air in the auxiliary cylinder isthrown into the air-cylinder and increases the quantity or volume of airin the air-cylinder by the amount of the air in the auxiliary cylinder.If, as in the drawings, the auxiliary cylinder is of the same capacityas the aircylinder, then when the piston commences to compress the airthere will be two volumes or double the quantity of air in theair-cylinder, and consequently double the amount of compressed air whenthe piston has compressed the air to the required degree.

By my improved compressor, therefore, at every stroke of the piston Iobtain a greater volume or quantity of compressed air, depending on thecapacity of the auxiliary chamber, and, furthermore, I obtain thisincrease by use of the exhaust-steam, which before was allowed toescape.

Surrounding the cylinder A is a water-j acket, W. to prevent the heatingof the air-cylinder.

What I claim is 1. In a compressor for compressing air, an air-cylinderhaving at one end of the compres sion-chamber in which the air iscompressed, and substantially opposite to the exhaustvalves, anauxiliary chamber capable of being filled with atmospheric air andsituated below and opening into the compression-chamber above the pistonin the latter when in its lowest position, and provided with a pistonactuated by exhaust-steam from the engine, adapted and arranged to forcethe atmospheric air in the auxiliary chamber into the compressionchamberin front of the compression-piston in the latter, substantially as andfor the purpose set forth.

2. In a compressor for compressing air, the combination, with theair-cylinder A, having the piston P, in which the air is compressed, ofthe auxiliary cylinder B, capable of being filled with atmospheric air,situated at the end of the air-cylinder substantially opposite to theexhaust-valves and opening into the aircylinder in front of the piston Pwhen at its lowest position, and provided with the piston C, adapted tobe moved by the rods D, for the purpose of forcing the atmospheric airin the cylinder into the air-cylinder A in front ofthe piston P, and ofthe cylinder E, capable of being filled with exhaust-steam from theengine and having the piston F, connected with the rods D and soarranged as to be acted upon by the exhauststeam to move the piston (J,substantially as described, and for the purpose set forth.

3. In a compressor for compressing air, the combination, with theair-cylinder A, in which the air is compressed, provided with theopenings K and tubes H, and having the piston 1?, containing the valves1), of the auxiliary cylinder B, capable of being filled withatmospheric air and opening into the cylinder A, through the tubes H andvalves 1), in front of the piston P, when in its lowest position, andprovided with the piston 0, arranged to be moved by the rods 1), for thepurpose of forcing the atmospheric air in the cylinder B into theaireylinder A in front of the piston P, and of the cylinder E, capableof being filled with eX- haust-steam from the engine and having thepiston F, connected with the rods 1), and so arranged as to be actedupon by the exhauststeam to move the piston G in the cylinder B, and ofthe buffers L, having the screwrods L and the pads 0, and containing thepistons Z, having the rods Z, and connected with the piston F by therods G, so as to move with the latter, substantially as described, andfor the purpose set forth.

Signed at New York, in the county of New York and State of New York,this 23d day of May, A. D. 1887.

WVILLIAM T. FORSTER.

W it-messes:

BENJ. E. SMYTH, J AMES '1. LAW.

